Fission gas puncture and sampling is performed using the HFEF gas assay, sample and recharge (GASR) system. The system comprises a 150-watt Nd-YAG pulsed laser, shielded optical feed-through, a mechanical vacuum pump, calibrated volumes, gauges and controls. Fuel elements or capsules are positioned on the laser by a clamp onto a gasket. The gasket provides a seal between the element and laser seal head. Void volume is determined by a series of backfills into the punctured fuel rod and expansions into the GASR system. The fuel rod internal gas pressure is derived from the void volume measurement and fission gas puncture pressure measurement. Fission gas samples are sent to the Analytical Laboratory, where they are analyzed by a gas mass spectrometer to provide krypton (Kr) and xenon (Xe) isotopic and total elemental composition. The rodlet void volume and internal gas pressure uncertainty is ≤ +/- 5% in the range of 0.03 to 60 liter-atmospheres. The isotopic and elemental analysis uncertainty is +/- 1-5%, depending on the relative abundance of the analyte.
equipment provides the ability to puncture cylindrical capsules or fuel
elements in their plenum regions to measure free volume and pressure, and gather
a sample for gas composition and isotopic analyses.
Pressure and Vacuum Instrumentation